Bituminous compositions and process for making same



- Patented May 3, 1938 UNITED STATES PAT NT- OFFICE p'rrummous comrosmons AND raocnss roa MAKING sum 7 James Kart Hunt and Joseph Barrel Shipp, Wil-' mington, Del., assignors to E. I. du Pont de Nemonrs & Company, Wilmington, Del., a corporation of Delaware No Drawing. Original application September 19, 1933, Serial No. 690,170. Divided and this ap-. plication February 2, 1935, Serial No. 4,632

8 Claims. (CI. 91-70) It is common practice inthe petroleum industry to distil crude oil, leaving a residue of asphal- 10 tic material behind. The properties of this residue will depend somewhat upon the point to which the distillation is carried. In this sense the properties of the petroleum bitumen may be said to bemodified by distillation. Such distillal5 tions of bituminous materials derived from pctroleum are not, however, useful for the purposes of the present invention which is concerned only with the heating or partial distillation of certain naturally occurring bitumens. We have found that coating compositions containing bituminous materials derived from petroleum are, with respect-to both gloss and durability, iar inierior to our improved compositions containing the processed asphaltites described herein. Bituminous materials of all kinds, including oils, asphalts, and coal, have also been destructively distilled for-the production or liquid and gaseous hydrocarbons and coke. In these processes the distillation is carried to coke formation and a liquid hydrocarbon such as gasoline or. oil is obtained as a distillate.

Volatile hydrocarbons have been produced by the partial distillation at temperatures of -680- 860 F. of parafflnic, and bituminous" substances such as resinous extracts from petroleum and low temperature tars, vitriolic mud, and natural asphalt waxes, and by the purification of bituminous compounds by distilling with analkaline earth at 572 F. These processes are not concerned with 40 the asphaltites or the present invention, nor are they concerned with the properties and utility of the residues. These processes are concerned only with the production of liquid hydrocarbons such as gasoline and-oils. The residues, where mentioned at all, are coke. The materials treated are reierred to as natural waxes, resinous extractsfrom petroleum and low temperature tars, bituminous, asphaltic, and parafllnic substances.

Processes for increasing the solubility of gil- 60 sonite and for increasing the fixed carbon and iodine numbers of various asphalts by heating the asphalt at low temperatures and for short periods of time are also known. The mild treatments as given in these processes do not, how- I ever, produce the results obtained by processing;

under the conditions of the present invention,

where the temperatures and time of treatment are such that gloss and durability are greatly enhanced. v

Wurtzilite and elaterite have also been heat 5 treated to render them fusible and soluble.

These bitumens are, however, pyrobitumensand not asphaltites. Furthermore, the products obtained are inferior in coating compositions to even untreated asphaltites, with which the present inlo vention is-concerned.

Other methods recorded for treating bitumens include thepreparation of diificultly fusible masses from Trinidad asphalt by distillation of 10% volatile matter. It is to be, observed that the same. 15

treatment of an asphaltite such as gilsonite lowers rather than raises the melting point (see Example 1),

Summing up, the prior art includes various methods for processing bitumens, but the treatment of asphaltitesas disclosed herein, and the discovery that markedly improved enamels may be made from the products of this treatment, has not been known hitherto. S

This invention has as an object the production 25 of improved bituminous material particularly suitable for the manufacture of coating composi-' tions. A further object is a process for treating bitumens of the type known as asphaltites. Another object is the preparation of improved coat-, ,30 ing compositions. A still further object is the manufacture of articles coated with a film of asphaltic nature which possess to a high degree the properties most desired in these articles such as high gloss retention and enhanced durability. 35 Other objects will appear hereinafter. w

These objects are accomplished by a special processing of a bitumen of the asphaltite type and formulating the processed asphaltite int'o coating compositions. v We have discovered that the naturally occurring bitumens" defined, by Abraham (Asphalts and'Allied Substances, D. Van Nostrand Co., 3rd edition, 1929, pages 36, 37, 164, 644, and

645) as asphaltites are remarkably improved 45 by partially distilling at a temperature not under 680 C., and preferably between-698 and 752 F. The extreme upper limit is probably very close to 752 Fraud should in no case be so high that a product incompatible with oils and/or thinners is produced. Temperatures as low as 680' F. sometimes produce the desired properties in the asphaltite. However, temperatures under 698 F. require a period oi time so long that it is "not practical. =From 5 to 50% of distillate is removed 'natural asphalts the softening the native asphalts to the asphaltites.

in the course of three to tenhours and the residual bitumen has yery different properties than the starting materials.

We wish to make it clear that the distillation referred to herein is not merely a voiatilization of material as it exists in the raw asphaltite. In fact, asphaltites contain very little volatile material as such, as evidenced by the fact that gilsonite, glance pitch, and grahamite lose less than 2% volatile on heating to 325 F. The present process involves an actual cracking of the bitumen, and removal of the volatile matter formed as a result of the cracking.

Asphaltites include gilsonite, glance pitch, and grahamite and, as defined in the reference just mentioned, are a species of bitumen; they are dark-colored, comparatively hard and non-volatile solids composed principally of saturated hydrocarbons substantially free from oxygenated bodies and crystallizable paraflines; sometimes associated with mineral matter, the non-mineral constituents being fusible and largely soluble in carbon disulfide.

The raw materials used in the preparation of our improved enamels are asphaltites as exem-' plified by gilsonite, glance pitch: (of which Barbados manJ'ak is an example), and grahamite. Asphaltites are differentiated from native or on the one hand, and from asphaltic pyrobitumens on the other hand, on thebasis of certain physical and chemical characteristics, e. g., fusing point and fixed carbon content. The asphaltites have a softening or fusing point of from 230" to 600 F. (Kramer- Sarnow fusing point method, details of which are given on page 682 of Abraham) or from 270 F. to 625 F. by the Ring and Ball method (details of which are given on page '687 of Abraham). According to page 165 of Abraham, gilsonite runs fairly uniform in composition and has a fusing point of 230 F. to 350 F. (K. 8: S. method) or 270 F. to 400 F. (Ball and Ring method).

Asphaltites (gilsonite, glance pitch, and grahamite) as a class differ from native asphalts in-that the latter have softening or fusing points definitely under those of the asphaltites. Thus, Trinidad asphalt, a typical native asphalt. has a softening point around 188 F. by the K. 8: S. method of 206 F. by the Ring and Ball method. (See Abraham, page 135.) As indicated above, however, there is not always a sharp break in point, values as one proceeds from The asphaltites are distinguished'frofn asphaltic pyrobitumens" (elaterite, wurtzilite, albertite, and impsonite) by the fact that the latter are infusible, i; e., cannot be fused without decomposition. i

Our method of improving gilsonite, or other asphaltite, consists in heating the bituminous material to a temperature of 698-752 400 C.) for 3-10 hours in a suitable vessel. Obviously higher temperatures in the range 698-752" F. require a shorter time of heating, and lower temperatures in this range a longer time. The exact optimum conditions are best determined for each asphaltite by simple experiment. In no case should the treatment be so drastic that incompatible products are obtained. It is obvious that different sized batches will require difi'erent periods of time for bringing to the critical temperature range. Either an open kettle, ora

tained because of operating difficulties at a tem-- perature of approximately 698 F. (370 C.) volatile matter is formed by the cracking of the bitumen. If the equipment includes a condenser, this volatile material may be collected as a light waterwhite or yellow liquid consisting of a mixture of various hydrocarbons with considerable unsaturated material. The actual removal of volatile products formed is not necessary-but the amount removed affords a convenient method of following the course of the reaction. If the process is carried out at atmospheric pressure, there may be some variation in the amount of distillate recovered (when the kettle is equipped with a condenser), or in the loss in weight (with or without a condenser). .If the loss of volatile matter formed is used as the criterion for following the I reaction, it is necessary that a volatile loss of at grainy", and may become unduly thick on aging.

The optimum appears to be about- 20% distillate when the kettle is equipped with condenser, or

25% volatile loss when kettle is not equipped with a condenser. The apparent discrepancy may be explained by the fact that non-condensable volatile matter, such as permanent gases, is also formed during the treatment. When the operation is carried out in an open kettle and loss of volatile matter determined by difference in weight before and after processing, these non-condensable gases show up as a weight loss, but when a kettle equipped with a condenser is used, these permanent gases are not condensed and therefore are lost. In other word, 20 lbs. of collected distillate might correspond to 25 lbs. weight loss from the asphaltite, assuming the formation of 5 lbs. of non-condensable volatile.

In general, processing under the critical conditions just given causes an increase in fixed carbon content of the asphaltite. This increase is most pronounced with gilsonite (see Example 1) and less so with glance pitch (see Example 2). It is believed that a change in chemical constitution (as reflected by increase in amount of fixed carbon) is responsible for the greatly increased utility of the processed asphaltites. These chemical changes are also reflected by lowering of fus I ing point and increase of iodine number.

Fixed carbon content as used herein, has the conventional meaning, and is determined by the method given by Abraham Asphalts and Allied Substances, page 711. The fixed carbon content of gilsonite, as treated in Example 1, changes from 18% to 24% and this represents a percentage.

final amount-original amount original amount In other words, the above-quoted expression does not represent an absolute figure, but a relative one, which is based on the original amount of fixed carbon. I

The percentage increase in fixed carbon of the asphaltite is, we believe, the real criterion for obtaining products which form highly improved films with resins, oils, etc. This increase in the per cent of fixed carbon by treating according to the present process, is critical in the following sense. The fixed carbon cannot be increased beyond certain limits, depending upon the particular asphaltite used. without obtaining incompatible products. Thus, untreated gilsonite. with a fixed carbon content of 18%, can be processed to a maximum fixed carbon content of about 30% a (a percentage increase of 67 /3). Efforts to increase the fixed carbon of this material much above 30% results in a product which is not compatible with resins, oils, and thinners. Untreated.glance pitch, with an original fixed carbon content of 25%, can be processed to a maximum of about 35% of fixed carbon (9. percentage increase of 40%) Further processing results in an incompatible product. Grahamite with an original fixed carbon of around 44% can be processed only to about 50% (an increase of 14%).

The lower limit in the increase in percentage of fixed carbon is determined only by the degree of change required to give practical improvement;

Any increase in fixed carbon gives an improved product and the greater the increase in fixed carbon up to the point of incompatibility the greater the improvement. The lower limit for definite and practical improvement varies some what with the different asphaltites, as is shown from. the following table.

according to Example land represents the period of time for the gloss and durability to be reduced to the fair" rating.

Thus it is seen that gilsonite should be processed to a percentage increase in fixed carbon of at least,20%, making the range for improvement about 20-65%. Likewise glance pitch should be processed to a percentage increase in fixed carbon of at least 8%, and the range for-definite improvement is about 840%. Grahamite has not been studied extensively, but we have found that a percentage increase in fixed carbon of 10-15% produces a definitely better product for preparing enamels. 1

The following examples are illustrative of methods for carrying out the invention. The starting material in Example 1 is the naturally .occurring bitumen gilsonite coming from the inner part of the vein and classed as selects.

Gilsonite is widely used in paints and enamels,

but it is recognized that compositions based upon this bitumen lose their gloss in a short time.

Exempt: 1

Gilsonite was heated at around l--'l25 F. in

a vessel fitted with a downward condenser to collect the distillate. During eight hours, of distillate was collected calculated on the weight of bitumen taken. The properties of the result ing product were quite different from the properties of the original materialas is shown-in the following table:

,The fusing point was determined by the Ball and Ring method; see Abraham's Asphaits and Allied Substances", 3rd edition (1929) p. 687. The treatment of Example 1 causes a percentage increase in fixed carbon of 33%.

, The bituminous residue obtained by the treatmentoutlined above was made into a baking enamel by the formula given below:

7 Parts by weight Treated gilsonlte 200 Resin .240 Kerosene 270 Hi-fiash naphtha 90 Drier 12 To make this enamel the treated gilsonite is heated to around 600 E, cooled to 575 F. and the resin, previously heated to 250 F., added. The kerosene and Hit-flash naphtha are mixed and added to the asphalt-resin mixture. The drier is added after the enamel has cooled.

The resin was made from:

Parts Glycerin 7 58 Sodium hydroxide 12 Linseed oil 560 Rosin- M 78 Phthalic anhydride 124 To make this resin the sodium hydroxide is dissolved in a small amount of water ands'tirred into the glycerin. The linseed oil is then added and the mass heated to 480 F. and held at that temperature for 1-2 hours, or until alcoholysis has' taken place. The rosin and phthalic anhydride are then added in the order named and the preparation completed by heating at 460 F. for three hours.

Instead of the above resin, others of a similar or different nature can be used. The rosindrying'oil modified p yhydric alcohol-polybasic acid resins see to be most satisfactory. The amounts of resin and oil croll acids) can be varied, with compensating changes in proportions of other ingredients. The po y i drlc alcohol-polybasic acid resins are generally preferred to other types and may he modified by one or more of the common ingredients used in 'their manufacture. These are of three types; esters, such as fatty oils (linseed oil, China-wood oil, cottonseed oil, castor oil, coconut'oilLdlbutyl phthalate, triacetin, etc; monobasic acids,

' such as rosin and other natural acidic resins,

fatty oil acids, stearic acid, oleic acid, hutyric,

acid, benzoic acid; and monohydric alcohols, such as butyl, benzyl, oleyl, ethoxy ethyl, cyclohexyl. etc. The polyhydric alcohols used may be glycerol,. glycols, so'rbitol, pentaerythrltol, etc.; the

polybasic acids may be phthalic, succinic, adipic,

maleic, citric, diphenic, qulnclinic, etc.

, To make this drier the man and linsecdoil fatty acids are melted together at 350 F. and the basic ferric acetate stirred in slowly. The temperature is-raised to 420 I". and held at that point until solution is complete. The Ill-flash naphtha is' then added. Other driers, such as coba lt, manganese, and lead, while satisfactory,

are less suitable.

' v It is of interest. and slgnificant, that in enam- 7 els of the typedescrlbed above, and also those which follow, the distillate from processed asphaltlte may be used as thinner, replacing all or a portion of the kerosene and naphtha. 5 Enamels based on distilled gilsonite. and thus thinned with the gilsonite distillate show the same superior durability as when kerosene and naphtha are used as thinner. This demonstrates that the process is not one of simple dis tillation resulting in only a concentrated bitumen, since it this were the case the durability (as reflected by gloss retention) of the enamels thinned with gilsonite distillate, and based on processed gilsonite, would not be superior to that of enamels'based on the unprocessed gilsonite.

. Theilgures in Table I show that enamels from processed gilsonite, thinned with its volatile decomposition products or with other thinners, is superior to unprocessed gilsonite.

Exam 2 A sample of glance pitch having a fusing point of 343 F. (R. 82 B. method) was distilled at Y around 700 F. by the same method as that described above for gilsonite until 10% of distillate had been removed. This treatment causes an increase in fixed carbon content of from to or a, percentage increase of 20%. The processed glance pitch was made into an enamel 30 by the same formula as given above for gilsonite under Example 1, and panels were made and exposed to the weather along with controls similarly prepared from untreated glance pitch (see Table II). The enamel from the treated bitumen was greatly superior in glass retention to the enamel prepared from untreated bitumen, as shown by the figures in Table II.

v EXAMPIE 3 Varnish for rubber-coated fabrics Parts by weight Processed gilsonite 100.00 Solvent naphtha 132.79 Turpentine 120;00 Raw linseed oil 120.00 Iron resinate 16.41 The gilsonite was processed by heating it in a kettle equipped with condenser at about 700 F. 50 for 5-8 hours to a volatile loss of about 25%.

In order to make the varnish from. these in gredients the processed gilsonite is heated to 500 F., allowed tocool to 425 F., and equal weight of solvent naphtha added and the mixture stirred until the gilsonite is dissolved. To this solution is added 240 parts by weight of a 50% solution of linseed oil in turpentine and 16.41 parts by weight of iron resinate dissolved in 32.79 parts of solvent naphtha, the latter soso lution containing 2.44% iron. 1: additional thinfabrics, more particularly ner is required, the

varnish is d for use on coated rumba-coated fabrics .of the kind used as material for automobile tops. Inmakingthis'type OtarflchtheVarnishisaD- plied directly over the fabric, and the system then baked at a temperaro'ture suitablefor vulcanialngthe rubber, e. g., MO-370 F. for 2-4 hours, upon the composition of the rubber compound with which the fabric is coated. Our preferred process for coating rubber-coated fabrics with the above varsolvent naphtha, turpentine, or distillate from prgilsonite maybe 75 nish involves the application of an intermediate around 700 F. in a closed kettle with condenser uncured rubber-mooted point around 830 1'. (R. h B. method). is heated coat of oil varnish to the fabric, allowing this oil varnish to dry at ordinary temperatures (or force-dry at 240-270 F. for 15mm. to one hour), after which the final coat consisting of the above bituminous varnish is applied and the system 5 baked at 240-270" F. for 2-4 hours, depending upon theicomposltion of the underlying rubber compound.

Exsmu: 4

High heat lender enamel Parts'by weight Processed gilsonite 450 F wood'rosin Lump burnt umber 1? Manganese resinate L' Alkali refined linseed oil 213 Refined menhaden oil 213 Kerosene 605 .V. M. 8: P. naphtha.. 167 20 Mineral spirits 118 The gilsonite was processed by heating it at about 700 F. to a loss of about 2025'% volatile matter in a closed kettle equipped with condenser. 25

The enamel is made from these ingredients as follows: The mixed oils are treated with the lump burnt umber (suspended in a wire basket) for 2 to 2 /2 hours at 600 F. After standing 30 about one day, the processed gilsonite, wood resin, and manganese resinate are added and the mixture heated to 600 F., then cooled and reduced with thinner. If a lower viscosity is required, additional kerosene may be used.

This enamel, over a suitable undercoat, e. g., a 35 rubber first coat is baked hour at 420 F.

EXAMPLE 5 High heat fender enamel 0 An enamel having excellent gloss retention characteristics may be prepared by substituting processed glance pitch, preferably a South American glance pitch or Barbados manjak (heated at to a loss of 20-25% volatile) for the processed gilsonite for Example 4 above. No substantial change in cooking schedule for the oil-rosinprocessed glance pitch mixture is necessary, although it should be borne in mind that the glance 50 pitches in general (including processed material as well as the raw) body relatively quickly at high temperatures, thus necessitating in some cases a reduction in temperature and/or time of heating over that when gilsonite is used.

Exlurvu: 6 Oil time black baking japan.

Parts by weight m Processed glance pitch 150 Alkali refined linseed oil 320 Lump burnt umber 20 Lump Prussian blue 5 Manganese resinate 4 Kerosene 257 Mineral spirits 246 The pitch. preferably Barbados manjak or a South American glance pitch having a-iusing at. about 700 1''. to a loss of about 20% volatile. Gilsonite processed by heating at around 700 1". to a 20-26% volatile loss may also be used.

To make this baking japan, the oil is heated with the timber (suspended in basket) for 3 to 4 hours at 600 F., allowed to cool to 300 F. and

the processed glance pitch,- Prussian blue, and

manganese resinate added. The mixture is then heated at around 350 F. until the processed 5 glance pitch is being carried to 550 F. The product is cooled and reduced with kerosene and mineral spirits. If necessary, it may be thinned with additional kerosene to proper consistency for dipping. A suitable baking schedule is 2 hours at 450 F.

EXAMP'LE 7 Bituminous varnish (without oil or resin) Parts'by' weight Processed gilsonite 350 Manganese dioxide 14 Turpentine 105 The gilsonite was processed by heating at ap- 29 proximately 700 F. for 6-8 hours to a loss of about 25% volatile.

In making the varnish the processed gilsonite is melted by heating to approximately 460 F. The manganese dioxide is added gradually with 25 constant stirring. The temperature is then carried slowly to 575 F and held at this point for 10 or 15 minutes, after which the mixture is cooled and thinned with turpentine, mineral spirits, or the distillate from processed gilsonite.

EXAMPLE 8 Kaari black baking japan Parts by weight 5 Processed gilsonite 200 Kaurl resin 300 Alkali refined linseed oil 190 Lump burnt umber 5 Turpentine 600 4 Mineral spirits 150 The gilsonite was processed by heating at 700 F. for 5-8 hours to a 20-25% loss of volatile.

These ingredients are combined as follows. The processed gilsonite is melted by heating to approximately 450 F., the Kauri (which may be used in the form of dust) then added and the mixture carried to about 500 F. where it is held until the resin is in solution '(usually 30 to 35 minutes). The oil, with which umber has previously been incorporated, is preheated to around 450 F., added to the resin-gilsonite mixture, and

, the whole heated to around 500 F. for 1 to 1 /2 hours. The product is cooled and reduced with thinner. The distillate from the processed gil- 55 sonite may also be used as thinner, replacing all,

or a portion, of the turpentine and mineral spirits. v

If lower viscosity is desired, additional thinner -can be used, preferably turpentine (either gum spirits or wood turpentine), or distillate .from processed gilsonite. Enamels should be baked for 2 to hours at 350 F.

Exam 9 M aniak baking japan Parts by weight Processed glance pitch F wood ros 50 7o Lump burnt umber 1 18 Manganese resinate 6 Alkali refined linseed oil 426 Kerose Y 605 vim. ar. naphtha 167 75 Mineral spir melted, the temperature finally- 1 18 good adhesion to steel and its good durability,-

The pitch, preferably Barbados manjak or a South American glance pitch, having afusing point of around 350 'F. (R. & B. method), is processed by heating in a closed kettle with condenser at about 750 F. for 6-8 hours to a loss of about 20% volatile.

To make this baking japan, the linseed oil is heated with the umber (suspended in basket) for 3 hours at 600 F. In the meantime, the processed glance pitch is melted in another kettle, and

heated at 400-.450.F. for 4 to?) hours. The oil (which has been permitted to cool to 400-450 F.) is then run into the processed glance pitch, the rosin and manganese. resinate added, the temperature raised to 500 F. and the whole cooled and reduced with thinner. If lower viscosity is desired, additional kerosene, or distillate from processed asphaltite, may be used.

This enamel, over a suitable undercoat (e. g., so-called rubber first coat), is baked for V, hour at 420 F.

EXAMPLE 1O G'rahamite baking enamel Using the formula shown under. Example 9, an enamel having good gloss retention may be made by substituting processed grahamite for the processed glance pitch of Example 9. (The grahamite is processed preferably in a closed kettle with downward condenser at about 700" F. for 6-8 hours, or to a volatile loss of about 20%.) A

relatively low-fusing grahamite (370-460" F., R.

81 B. method) is preferable, such as the grahamite from the Vistabella mine in Trinidad, but grahamite having a higher fusing point may be used by "resorting to a-somewhat higher temperature for melting out the processed grahamite, and fiuxing the grahamite with the rosin content of the enamel. The processing produces an appreciable increase in percentage of fixed carbon. Care should be exercised that the enamel does .not become too thick during cooking, which, as

those skilled in the art fully appreciate, is likely to happen with either glance pitch or grahamite.

To make this enamel the base is ground in a ball mill until the proper dispersion of pigment is obtained. The base is then mixed with additional enamel of Example 4 andreduced with mineral spirits. II lower viscosity is required, additional mineral spirits, kerosene, or distillate from processed as'phaltlte may be used.

A single coat of this enamel may be baked'in /2 hour at 450 F. An enamel'pigmented in accordance with 'the'above formula is particularly suitable as a primer (rubber first coat) for use under non-pigmented baking enamels of the types shown in the previous examples because of its heated to 500 .duced.

EXAMPLE 12 Varnish for coated fabrics Parts by weight The gilsonite was processed. by heating it at approximately 700 F. for 5-8 hours to a volatile loss of 20-25%.

To make the varnish the processed gilsonite is F., allowed to cool to 485 F., the solvent naphtha added, and stirred until the processed gilsonite is dissolved. The bodied Chinawood oilturpentinedrier solution (see below) is then. added. If additional thinner is needed solvent naphtha, turpentine, or'distlllate from processed gilsonite may be used. I

The China-wood oil--turpentine-drier solution is, made as follows: The raw wood oil is heated to 385 F. and the lead and manganese resinates added slowly with constant stirring. The oil is heated to 425 in the course of about one hour and held for about minutes. It is then cooled and reduced with turpentine.

The varnish is applied to the fabric in the manner indicated in Example 3.

We have found also that simple heat treatment of glance pitch in an autoclave at around 700 F. for a period of about 6 hours gives rise to an improvement in the bituminous material, as evidenced by superior gloss retention of fender enamels based on such treated glance pitch. In the autoclave treatment there is generally no distillation of volatile matter. However, it isfeasible for the autoclave to carry a condensing system maintained at the same pressure as the autoclave; such an arrangement permits a closer check on the progress of the reaction through the observation of the amount of distillate pro The asphaltite may be heated in the outoclave either alone or with'small amounts of liquid hydrocarbons, e. g., kerosene or crude oil.

While we do .not wish to be limited to any theory ofOI explainingthe improvement in 'our processed asphaltites, we believe that the bitumen is first cracked by the heating process. This cracking results in'the formation of highly unsaturated molecules which combine with each other, or undergo internal rearrangement, which results in a more highly polymerized'and stable product. This recombination or repolymerization is apparently not complete, since the final prodnot is still more unsaturated than the starting material, as indicatedby the higher iodine value of the processed asphaltite (see under Example 1).

Probably the repolymerization occurs most rapidly at a temperature below the cracking temperature, and we believe the repolymerization, and perhaps the cracking also can be catalyzed by appropriate materials. Thus better results appearto beobtained in co r and aluminum/vessels than in iron. This suggests the addition of finely divided metals and sulfur-insehsitive crack ing catalysts.

While our processed asphaltites are designed chiefly for use in enamels where high initial gloss.

and retention= of glossyai e important, they may also be used to advantage in any;type offbituminous finish where good durability characteristics in general are desired. Our. processed asphaltites may be used to advantage in comblnatlonwith any of the oils commonly used in bituminous coating compositions, e. g., linseed oil, China-wood oil, soya bean oil, menhaden (fish) oil, perilla oil, etc. Our processed asphaltites may also be used in combination with any of the varnish resins (natural or synthetic) commonly used in bituminous coating compositions','e. g:, oil-soluble phenol-formaldehyde and coumarone resins, rosin, kauri, etc., and with the pigments ordinarily ground into such compositions, e. g.,' carbon black, lampblack, etc.

.. The improved luster-retaining characteristics of our coating compositions will be apparent from the following comparison based upon actual tests:

The following table shows the gloss-retentive properties of baking enamels, prepared, according to the formula given in Example 1, from treated I wurtzilite, untreated gilsonite,

ed as in Example 1. The enamels were flowed on steel panels and baked for hour at 450 F., over a bituminous enamel undercoat such as is given and gilsonite treatin Example 11, similarly baked. These panels,

along with suitable controls prepared in the same manner from untreated gilsonite, were exposed to the weather. The exposure tests were in a sense accelerated since the panels were exposed continuously under the most rigid atmospheric conditions, namely, at an angle of 45 facing south. When first prepared these panels had a high gloss, which is a desirable feature in baking enamels, especially in enamels for automobile fenders. It is also desirable that this glossy surface be retained for a long period. The panelswere examined at regular intervals and gradedor glc-s by comparison with five standard panels which were arbitrarily rated as excellent" good, fair", poor, and very poor" in gloss. The following table shows the gradings at various times for an enamel prepared from distilled gilsonite (as indicated above) and for the control enamel based on untreated gilsonite. It will be noted that the distilled gilsonite enamel is definitely superior to the control. The following table also shows that volatile material from the cracking of gilsonite can be used as a thinner with results equal to those obtained withordlnary thinners.

It will be apparent from the foregoing that v {the processed bitumen described herein makes possible the formulation of coating compositions, the films of which. possess the important advantages of increased durability and long retention of their initial high gloss.

The superior glass retention and durability of similar enamels based on treated glance pitch following table.

posed as described above.

Table II After exposure for Enamel based on Enamel based on time indicated original glance pitch treated glance pitch Weeks 1 -Excellent.-- Excellent.

4 do Do. 8-..-- do. Do. 12 Fair Good. 15 Poor Do. Z) do Do. 24 0 Fair. 28 n Do. 7 32 0 Do. 36 do Do.

. Weclaimz.

As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that we do not limit ourselves to'- the specific embodiments thereof except as defined in the following claims:

1. A composition of matter comprising the asphaltite prepared by heating gilsonite until the fixed carbon content thereof has increased 20 to 65%. a diluent and at least one film-forming material selected from the class consisting of fatty oils, and resins. I

2. An article of manufacture, having a coating comprising gilsoniteheated until the fixed carbon content thereof has increased 20 to 65%.

3. As a new article. of manufacture, fabric sheet material having a coating of dried varnish prepared by heating gilsonite until the fixed carbon content thereof has increased 20 to 65%.

4. As a new article, of manufacture, metal having a coating of baked varnish comprising gilsonite heated until the fixed carbon content thereof has increased 20 to 65%.

5. Process of preparing a coating composition which comprises the improvement of mixing gilsonite which has been heated at a temperature between 698 F. and 752 F., until the fixed carbon content hasincreased 20% to 65%, with a soluble rosin-drying oil modified poiyhydric alcohol-polybasic acid resin.

6. In a process of preparing coating compositions wherein a plurality of ingredients are mixed,

the improvement which comprises incorporating therein a processed asphaltite which-has been heated for 3 to hours at a temperature between 698 and 752 F. I

gilsonite which has been heated until the fixed carbon content has increased 'to with a -film-forming material selected from the class consisting of fatty oils, and resins.

8. Product of claim 2 in which the coating comprises film-forming material selected from the class consisting of fatty oils, and resins.

JAIME KARR HUNT. JOSEPH BARREL BHIPP. 

